The present invention relates to a deep-grooving chip-forming cutting insert.
A conventional deep-grooving cutting insert 10 for chip forming machining is depicted in FIGS. 1 and 2. That insert 10 includes a rear mounting portion 12 adapted to be secured in a holder, and a front cutting portion 13 including a cutting edge 14. The cutting edge, which extends perpendicularly to the direction of feed, is adapted to cut a groove having a width W.
The cutting edge includes a main portion 15 and a pair of corner portions 16 disposed at opposite ends of the main portion and defining the ends of the cutting edge. The corner portions are convexly curved, e.g., they define a corner radius R.
During a grooving operation, the cutting edge 14 produces a single chip which extends along the main portion 15 and the corner portions 16. Thus, it will be appreciated that the ends of the chip are slightly curved, so the overall total chip width is somewhat greater than the cutting width W of the cutting edge, which cutting width W corresponds to the width of a groove being cut. As the wide chip is pushed out of the groove, it rubs against the sides of the groove, whereby producing friction which generates heat that causes a hardening and deterioration of those groove sides. Also, it becomes increasingly more difficult to push the chips out of the groove as the groove becomes deeper, which adversely affects the condition of the cutting edge and thus, the tool life.
A grooving insert is disclosed in U.S. Pat. No. 5,975,812 wherein the main portion of the cutting edge is divided into three equal-length portions, the center portion of which is offset forwardly from the other two portions. The cutting edge portions cut respective chips of essentially equal width which interfere with one another as they leave the groove. Such a condition may develop vibrations in deep-groove cutting operations which adversely affect the ability to control the chips produced, and may lead to chip jam-ups and entanglements.
It would be desirable to provide a deep-grooving insert that minimizes the generation of frictional heat during a grooving operation.
It would also be desirable to provide a deep-grooving insert which is easier to control and avoids chip jam-ups and entanglements.